The invention relates to a method, a device and software for digital inverse multiplexing digital data.
In practice very many methods are know to send digital data, particularly digital data through a network. An example are digital data that are sent through the internet, but also digital telephone signals, such as for instance in case of cordless GSM telephones.
In practice also various methods and devices are known for inverse multiplexing digital data.
The data are sent in the form of data packets via a medium. This can take place via a physical cabling in for instance copper or glass fibre, or cordless, for instance via infrared or radio waves.
Because the capacity of data transfer, often coupled to bandwidth, of the media over which the data are sent is mostly too small, the data are often compacted. However, this has often appeared not to be sufficient.
Additionally many of these methods are aimed at optimising the data transfer between two computers. Moreover, many techniques require an overhead, and are not always as robust regarding the errors or failures of lines and other malfunctions.
It is among others an object of the present invention to at least partially solve these problems. To that end the invention provides a method for digital inverse multiplexing digital data, wherein a packet of digital data is split into:
a first flow wherein the packet of digital data is sent from front to rear;
a second flow wherein the packet of digital data is sent from rear to front, and;
a third flow, consisting of a flow of data elements obtained from each time a first data element of the packet of digital data from the rear part of the front subarea of the packet and a second data element of the packet of digital data from the front part of the rear subarea of the packet that are reduced into one third data element by means of a reversible operation.
Additionally the invention provides a device for sending a packet of digital data consisting of data elements, comprising:
a transmission module, adapted for transmitting the data elements;
a memory module, adapted for storage of the packet of digital data;
a reading module, adapted for reading each time two data elements from two parts of the memory module, one data element from the rear part of the front subarea of the packet, and one data element from the front part of the rear subarea of the packet;
an operator, adapted for converting said two data elements into one data element to be transmitted, and
a construction module, adapted for receiving the data elements of the reading module, supplying the data elements to the operator, and receiving the resulting data element from the operator and supplying the data element to the transmission module.
Additionally the invention provides a device for receiving a packet of digital data consisting of data elements, comprising:
a receiving module, adapted for receiving at least three flows of data elements;
a memory module, adapted for storage of the data elements;
an operator, adapted for converting two data elements in one data element;
a counting module, adapted for tallying the quantity of data elements that have been received from each flow;
a decision module, adapted for determining whether all data elements that are necessary for reconstructing the complete packet of digital data are present and to determine which part of the packet has to be determined by means of reconstruction, and
a reconstruction module for retrieving each time two data elements from the memory means, which is connected to the operator for supplying said data elements to the operator, discharging the resulting data element of the operator and writing the resulting data element to the memory module.
Additionally the invention provides software for receiving a packet of digital data that is sent in at least three flows of data elements, comprising:
a writing routine for writing the data elements of the flows of data elements to the memory means;
a counting module for tallying the quantity of data elements that have been received from each flow;
a decision routine for determining whether all data elements that are necessary for reconstructing the complete packet of digital data are present and to determine which part of the packet has to be determined by means of reconstruction;
an operator routine for converting two data elements into one data element, and
a reconstruction routine for retrieving each time two data elements from the memory means, for supplying said data elements to the operator routine, for discharging the resulting data element from the operator routine and writing the resulting data element to the memory means.
By splitting the data flow in several flows, wherein a first flow starts sending the data from the front and works its way to the rear, the second flow works from the rear to the front, and at least one third flow according to the invention is defined, the possibility is given to very quickly send data between and to for instance computers. Additionally, because of the specific way in which the flows are compiled it is not necessary to let others than the transmitter(s) and receivers communicate with each other. Possible different transmitter(s) do need not communicate with each other. Additionally no complex data processing is necessary to for instance tally when all data have been received.
Moreover, it is possible as a result of the invention to realise a fast and robust data transfer of a low overhead, also because a third check signal is compiled from the data.
In many cases the data connection is a-symmetrical: the transfer capacity is smaller than the receiving capacity. In the method according to the invention, the entire receiving capacity can be used despite the smaller transmission capacity. This may for instance be of importance in so-called streaming broadcasts through the internet, wherein through the internet digital radio broadcasts and in the future even television or video can take place. The data flows can also enter via various lines. For instance one data flow can for example enter via a telephone line, and another data flow via a cable, the electricity grit or cordless via GSM. It is also possible to let the data flows enter via one cable by means of physical multiplexing. The invention therefore actually offers a specific form of digital inverse multiplexing.
Inverse multiplexing according to the invention can take place at different levels, at micro level and at macro level, or simultaneously at different levels. A possible micro level is bit level. A possible macro level is the level of data packets that are merged into data at receipt, as known from connections that run via the internet.
In an embodiment of the method consecutive first data elements from the rear part of the front subarea are selected from rear to front. As a result even less overhead and control is necessary. In an embodiment thereof or of the method according to the invention consecutive second data elements from the front part of the rear subarea are selected from front to rear, which once more considerably simplifies the control. In an embodiment each time an immediately following data element is selected.
In one of the preceding methods the packet of digital data, if necessary supplemented to a packet that can be split into two equal parts, can be split into two equal sized parts. As a result fewer positions have to be tallied, and a simple method can be guaranteed.
In one of the preceding methods the first and second data elements are bits of the packet of digital data, and the third data element is the result of a single binary operation, preferably an XOR operation, on the first data element and the second data element. By means of a simple, reversible binary operation a quick and simple method can be realised.
In a embodiment according to any one of the preceding methods, the data elements of the first, second and third flow, respectively, are placed in a first, second and third data buffer, respectively. Thus the data buffers can have the size of half the packet of digital data. In this way a simple method can be realised with minimal memory means and control.
In another embodiment of the method the data elements of the first, second and third flow, respectively, are placed in one data buffer having the size of the packet of digital data. In this way optimal use is made of memory means available. In said embodiment the first flow can fill the data buffer from front to rear, the second flow can fill the data buffer from rear to front, and the third flow is duplicated, wherein one duplicated flow fills the data buffer from the middle to the front, and the other duplicated flow fills the data buffer from the middle to the rear. As a result very simple implementation is possible.
In another embodiment the data elements of the first and second flow are placed in a first data buffer, wherein the first flow fills the data buffer from front to rear, and the second flow fills the data buffer from rear to front, and the data elements of the third flow are placed in a second data buffer. This is for instance advantageous when the first or second flow are very fast. It is simply possible then to let that flow run beyond the half.
In an embodiment of a method as described above, either the first or the second flow can overwrite data elements already present in the data buffer originating from the third flow.
In an embodiment of the method a first, second or third device, respectively, sends the first, second and third flow, respectively, to a fourth device. The fourth device can send a signal to the first, second and third device when either the data buffer is full or the respective data buffers are full, or stops sending receipt confirmations as soon as the data buffer is full or the respective data buffers are full.
In a possible embodiment, for instance when transmitting or receiving streaming internet content or other sequential signals, the flows are almost simultaneously sent.
An embodiment of the method described above relates to a method wherein a transmitting device sends the first, second and third flow to a first, second and third receiving device, respectively, and wherein the first, second and third receiving device forward their respective flows to the other two receiving devices.
Additionally the invention relates to a method for sending a packet of digital data to a first device in an organic data network, wherein at least two transmitting devices in the data network simultaneously send complementary data packets to the first device and a third transmitting data device sends data packets to the first device that have been obtained from each time a first data element from the rear part of the front subarea of the packet and the second data element from the front part of the rear subarea of the packet which by means of a reversible operation have been reduced into one third data element, wherein the data packets of the transmitting devices form the packet when merged.
In an embodiment of this method the first device controls the transmission of the transmitting devices, and the first device forwards the data packet to at least one device in the data network, independent of the transmitting device or devices. As a result the method, the software or the device can be deployed in an organic network as described in Dutch patent 1017388.
Additionally the invention relates to a method for receiving a packet of digital data, wherein a receiving device provided with data storage means creates a data buffer in the data storage means the size of a packet of digital data to be received, and after that almost simultaneously receives a first flow, a second flow, and at least one third flow of data elements, wherein the receiving device fills the data buffer from front to rear with the first flow of data elements and fills the data buffer from rear to front with the second flow of data elements, and fills the data buffer from the middle to the front and to the rear with the third flow of data elements.
In an embodiment of this method the receiving device makes it known to transmitting devices of the flows of data elements when the front or rear half of the data buffer is full and the quantity of data of the third flow and the flow that does not fill the data buffer halfway yet together are sufficient to fill the other half of the data buffer.
Additionally the invention relates to a method for sending a packet of digital data, wherein a device provided with data storage means creates a data buffer in the data storage means, stores the packet of digital data in the data buffer, converts each time a first data element from the rear part of the front subarea of the data buffer and a second data element from the front part of the rear subarea of the data buffer into one data element by means of a reversible operation, and transmits said data element.
In an embodiment of one of the methods described above for either receiving or sending a packet of digital data at least three flows of digital data are almost simultaneously received or sent, respectively.
A device for receiving according to the invention can furthermore comprise a duplicating module, adapted for duplicating a data element and writing each of the duplicated data elements to the memory module.
Additionally the invention relates to software for sending a packet of digital data according to a method described above, wherein the software is provided with:
a construction routine for retrieving two data elements from the memory means, one data element from the rear part of the front subarea of the packet, and one data element from the front part of the rear subarea of the packet, and converting said two data elements into one data element by means of a reversible operation;
a transmission routine for transmitting the wanted flow of data elements, and
a stop routine for receiving and processing an instruction from a receiver of a flow of data elements to stop transmitting.
In an embodiment said software further comprises:
an instruction routine for receiving an instruction which of the flows of data elements has to be sent.
Preferably a device stops sending after receipt of a signal from the receiving device. As a result the coordination is again simple.
Additionally the invention relates to software provided with routines for carrying out the method according to one or more of the preceding claims. From the above description, in combination with the figures and their description, it will immediately be obvious to the expert which routines are necessary to that end, and how said routines have to work with respect to each other. Such software can of course be immediately implemented in hardware, for instance in a PROM, EPROM or the like, or entered into hardware, for instance at chip level in hardware logic.
Additionally the invention relates to a carrier provided with software as described.
Additionally the invention relates to a device, provided with software as described.
The invention is further elucidated on the basis of the figures that form exemplary embodiments of the invention. However, the invention is not limited to said exemplary embodiments.